Anchor Chain Weight

Discussion in 'Stability' started by Fanie, Jun 9, 2008.

  1. Fanie
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    Fanie Fanie

    Hello,

    The achor chain I intend to use on my 10m cat is 10m long and has an 8mm link thickness. I will have an aditional 20m of the same chain for when bad weather and high winds are under way.

    Is there a rule, or some kind of a measure as to the length and weight (chain size) such a chain should be ?
     
  2. charmc
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    charmc Senior Member

  3. Manie B
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    Manie B Senior Member

  4. Fanie
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    Fanie Fanie

    From an article I just read -

    SS becomes brittle when ageing, especially under cyclic efforts in salted water. In other words, you should replace your SS anchoring tackle much more

    I was wondering why everyone uses galvanized steel...

    So for my size boat it looks like it has to be 10mm chain, and at least 15m long... followed by anchor rope with some stretch in it. I hope I remember to pack the anchor :D

    Hi Manie.

    Thanks Charlie !!
     
  5. Guillermo
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    Guillermo Ingeniero Naval

  6. charmc
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    charmc Senior Member

    Fanie,

    SS does not like the chloride compounds in salt water, it will corrode and the effects accelerate with water temps above 25 C. OK for fittings and tackle above the waterline that can be rinsed off with fresh water after use. Galvanized is excellent until the coating wears off, but using SS anchor chain is paying a lot more for chain that won't last any longer than galvanized and may fail sooner. If you want a nicer appearance and longer life, you can buy polymer-based coatings to brush on, or just dip the chain. Lose some flexibility but adds to the chain life and looks nice, if that's a factor.
     
  7. Fanie
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    Fanie Fanie

    Thanks Guillermo and Charlie,

    I already know what I set out to find out, but you have an interesting site. Sorry I cannot view it optimally, I see you mention it is best viewed with a 17" monitor, and I have 19"'s... pity :D

    Ok Charlie, since it seems you have links to all the stuff I'm trying to finds out about, just send me ALL your links :D

    Polimer Paint... A paint made of acrylic resin or vinyl resin, or a combination of both resins, in a liquid form with water as the base; it spreads out in a layer, and the water evaporates to leave a continuous, flexible, and waterproof film of plastic.

    How durable and strong is it ?

    Polymer Paint Kills Bacteria and Flu Viruses - http://infectiousdiseases.about.com/od/faqs/p/polymer.htm

    Don't know if I'll go to such lengths just to be able to say ' My anchor chain kills bacteria and flue viruses'. Half the people is going to think you hit the viruses with the chain... ;) and since they are carriers... :D
     
  8. Landlubber
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    Landlubber Senior Member

    Fanie,

    Black steel chain looses up tp 25% of its strength when it is galvanised.
    If it is not galvanised it will loose this much anyhow as it rusts out.
    Hot dipped galvanising is still the most reliable anchor chain for the money, get yourself either L grade or P grade.

    Combined with nylon rope, you will have a reasonable anchor system.
     
  9. charmc
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    charmc Senior Member

    Of course, there are usually a few people for whom hitting with the chain is a good thing. :D. I didn't know about the killing of flues and viri, (Nuns drummed Latin into me when I was a lad ... can't get the damn stuff out of my head!) but I did forget another benefit: protects your topsides and deck from chain scratches, gouges, and rust stains, so not only is the coated chain pretty but it helps keep your boat pretty.

    Vinyl coating is what I meant. It is relatively thick, so the one drawback is that it reduces the flexibility of the chain, makes it act like a stiff cable. You can coil it, just not as tightly, and you can't just drop it in a pile. There are polymer coatings, more like a thick coat of paint. They give less protection but retain the normal handling characteristics of the chain. Here's a description: http://www.westmarine.com/webapp/wc...81?srccode=cii_13736960&cpncode=17-10621155-2
     
  10. Fanie
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    Fanie Fanie

    I got some prices and it seems the hot diped chain is more expensive than the 10mm 7x19 SS cable :mad: Maybe I must just use the cable instead :D But yes, it seems the hot dipped chain would be best.

    What would the difference between the long link and short link be ? I don't see how it could make any difference...

    I see on some of the boats the chain is dropped into a box. If it is spooled over the anchor rope would it make any difference ? I was thinking of making a winch where you can reel the anchor rope and chain on.
     
  11. charmc
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    charmc Senior Member

    Fanie,

    Why are you thinking ss cable/wire rope for anchor line? Its benefit is strength for weight and lack of give. No benefit in anchoring yachts; cable is used in very deep anchoring like offshore oil, but I've never seen it used to anchor a rec boat. Then there's all the moisture retained between the strands, source of corrosion for SS. It's normally a rigging and lifeline product. For 10 m or less length, I'd go with chain. Good to think outside the box, but everyone knows SS cable costs less, there's a reason chain is used.

    Long and standard links are just differences in construction. Long link is a bit lighter for the same length (fewer links). Chain winch sheaves are made for standard links; I don't think they will take long links. Spooling over rope on a rope winch? Maybe abrasion problems; no others, I think, if you're making your own winch.
     
  12. Fanie
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    Fanie Fanie

    I'm not ! 15m x 10mm hot diped chain it will be.

    Or maybe it is bulky and heavy... I'll have to see when I get the stuff.
     
  13. Landlubber
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    Landlubber Senior Member

    Yes, short link chain gives more weight per metre, naturally better for catenary. It is also stronger in ultimate strength.
     
  14. Patrick BLOSSE
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    Patrick BLOSSE La Terre entière.


  15. Tcubed
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    Tcubed Boat Designer

    Hate to go on a possibly controversial tangent here...But i will anyways.

    Personally, i am not keen on chain, as i feel that weight is more useful in the anchor itself. Instead of a 15 kg anchor with another 20 kg of chain on it, say, i would use a 30 kg anchor with no chain and the hold is ultimately much better and it is easier to get back onboard. When it is really blowing the catenary effect becomes insignificant so at that point you need the same scope as if using all nylon, but with no shock absorbing benefits. The only real advantage of chain it is very difficult to chafe so gives great security against bottom garbage etc.

    Myself i use an oversize polypropylene rope near the anchor. This makes it float up from the anchor when the wind is very weak and random, which tends to be when anchor rode snags on underater junk. If it does rub on something, because it is very oversize, it is also under very low stress and less vulnerable to chafing. This is still no guarantee and works good for me as i don't tend to spend much time at anchor. If longer than a week at anchor i rotate anchors. This keeps me on top of any changes that may be happening to my gear as well as preventing any incrustation of marine growth from fouling my gear.

    As for cable, yes it does get used on yachts and i would highly recommend it for yachts large enough to justify anchor retrieval machinery, say over 12 tons. Excellent strength to weight ratio, very chafe resistant, easy to store on a spool. Weights get clipped on for catenary by obligation which is easy to do but adds a a certain amount of complication, unfortunately. Successive weights get added to deal with stronger conditions. Ideally some of the sailboats' lead ballast itself. The wire must be galvanized. SS is dangerous.
    It's not for everyone but it is a neat option.

    Chain is good for anchoring a boat for extended periods with no one on board, but for myself, as i sail engineless and i don't tend to stay long in places it's not so good.

    With anchoring, though, the only things set in stone are minimum scope and anchor weight requirements, the rest is pretty personal,i would say.
     
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